Interference suppression in a radio transceiver device

ABSTRACT

There is provided mechanisms performed by a control device for suppressing interference in a received reception signal in a radio transceiver device. The radio transceiver device is configured to receive the reception signal as a radio reception signal and to generate a radio transmission signal. The radio transmission signal and the radio reception signal occupy at least partly non-overlapping frequency bands. A method comprises obtaining a transmission reference signal based on the radio transmission signal. The method comprises estimating an interference distortion component signal based on the transmission reference signal and on a model of nonlinearity in a radio circuit of the radio transceiver device. The method comprises suppressing interference in the reception signal by combining the reception signal with the distortion component signal.

TECHNICAL FIELD

Embodiments presented herein relate to interference suppression, andparticularly to a method, a control device, a computer program, and acomputer program product for suppressing interference in a receivedreception signal in a radio transceiver device.

BACKGROUND

In communications networks, there may be a challenge to obtain goodperformance and capacity for a given communications protocol, itsparameters and the physical environment in which the communicationsnetwork is deployed.

For example, radio link systems in some communications networks aredesigned as Frequency Division Duplex (FDD) systems. In FDD systems thetransmitted carrier frequency differs from the received carrierfrequency. The transmitted signal is commonly at a much higher powerlevel than the received signal. Hence, the receiver of a radiotransceiver device operating in a FDD system would saturate if thetransmitted signal of the radio transceiver device would leak into itsreceiver.

A diplexer filter (also known as a branching filter) is commonly used toprevent the transmitted signal from leaking with high power into thereceiver.

Such a diplexer is relatively expensive to manufacture, and constitutesa quite space-consuming component. Furthermore, FDD systems used forproviding microwave links are manufactured and sold for many differentfrequency bands, and it is therefore necessary to have at least onespecific diplexer per frequency band, due to the frequency dependency ofcomponents. Hence, the diplexer is commonly designed in several variants(many per frequency band) leading to high cost due to the diplexer assuch and the variant penalty cost.

There is thus a need for a less complicated mechanism for preventing thetransmitted signal of the radio transceiver device to leak into itsreceiver.

SUMMARY

An object of embodiments herein is to provide efficient mechanisms forsuppressing interference in a received reception signal in a radiotransceiver device.

According to a first aspect there is presented a method performed by acontrol device for suppressing interference in a received receptionsignal in a radio transceiver device. The radio transceiver device isconfigured to receive the reception signal as a radio reception signaland to generate a radio transmission signal. The radio transmissionsignal and the radio reception signal occupy at least partlynon-overlapping frequency bands. The method comprises obtaining atransmission reference signal based on the radio transmission signal.The method comprises estimating an interference distortion componentsignal based on the transmission reference signal and on a model ofnonlinearity in a radio circuit of the radio transceiver device.

The method comprises suppressing interference in the reception signal bycombining the reception signal with the distortion component signal.

Advantageously this method provides efficient suppression ofinterference in a received reception signal in a radio transceiverdevice. In particular, interference arising from cross-modulationbetween transmitted and received signals, due to the non-linearity inthe radio circuit, is suppressed.

Advantageously this method provides a simple mechanism for preventing,or at least countering/alleviating, leakage of the transmitted signal ofthe radio transceiver device into its receiver.

Advantageously this method reduces the total cost of the radiotransceiver device.

Advantageously this method requires only a few frequency indexes to bestored in the radio transceiver device which, in turn, gives lowproduction cost and less warehousing comparted to a radio transceiverdevice using a diplexer.

According to a second aspect there is presented a control device forsuppressing interference in a received reception signal in a radiotransceiver device. The radio transceiver device is configured toreceive the reception signal as a radio reception signal and to generatea radio transmission signal.

The radio transmission signal and the radio reception signal occupy atleast partly non-overlapping frequency bands. The control devicecomprises processing circuitry. The processing circuitry is configuredto cause the control device to obtain a transmission reference signalbased on the radio transmission signal. The processing circuitry isconfigured to cause the control device to estimate an interferencedistortion component signal based on the transmission reference signaland on a model of nonlinearity in a radio circuit of the radiotransceiver device. The processing circuitry is configured to cause thecontrol device to suppress interference in the reception signal bycombining the reception signal with the distortion component signal.

According to a third aspect there is presented a control device forsuppressing interference in a received reception signal in a radiotransceiver device. The radio transceiver device is configured toreceive the reception signal as a radio reception signal and to generatea radio transmission signal. The radio transmission signal and the radioreception signal occupy at least partly non-overlapping frequency bands.The control device comprises processing circuitry and a computer programproduct. The computer program product stores instructions that, whenexecuted by the processing circuitry, causes the control device toperform steps, or operations. The steps, or operations, cause thecontrol device to obtain a transmission reference signal based on theradio transmission signal. The steps, or operations, cause the controldevice to estimate an interference distortion component signal based onthe transmission reference signal and on a model of nonlinearity in aradio circuit of the radio transceiver device. The steps, or operations,cause the control device to suppress interference in the receptionsignal by combining the reception signal with the distortion componentsignal.

According to a fourth aspect there is presented a control device forsuppressing interference in a received reception signal in a radiotransceiver device. The radio transceiver device is configured toreceive the reception signal as a radio reception signal and to generatea radio transmission signal.

The radio transmission signal and the radio reception signal occupy atleast partly non-overlapping frequency bands. The control devicecomprises an obtain module configured to obtain a transmission referencesignal based on the radio transmission signal. The control devicecomprises an estimate module configured to estimate an interferencedistortion component signal based on the transmission reference signaland on a model of nonlinearity in a radio circuit of the radiotransceiver device. The control device comprises a suppress moduleconfigured to suppress interference in the reception signal by combiningthe reception signal with the distortion component signal.

According to a fifth aspect there is presented a computer program forsuppressing interference in a received reception signal in a radiotransceiver device, the computer program comprising computer programcode which, when run on a control device, causes the control device toperform a method according to the first aspect.

According to a sixth aspect there is presented a computer programproduct comprising a computer program according to the fifth aspect anda computer readable storage medium on which the computer program isstored.

According to a seventh aspect there is presented a radio transceiverdevice 100 configured to receive the reception signal as a radioreception signal and to generate a radio transmission signal. The radiotransmission signal and the radio reception signal occupy at leastpartly non-overlapping frequency bands. The radio transceiver devicecomprises a control device for suppressing interference in a receivedreception signal in the radio transceiver device according to any of thesecond aspect, the third aspect, or the fourth aspect.

It is to be noted that any feature of the first, second, third, fourth,fifth, sixth and seventh aspects may be applied to any other aspect,wherever appropriate. Likewise, any advantage of the first aspect mayequally apply to the second, third, fourth, fifth, sixth, and/or seventhaspect, respectively, and vice versa. Other objectives, features andadvantages of the enclosed embodiments will be apparent from thefollowing detailed disclosure, from the attached dependent claims aswell as from the drawings.

Generally, all terms used in the claims are to be interpreted accordingto their ordinary meaning in the technical field, unless explicitlydefined otherwise herein. All references to “a/an/the element,apparatus, component, means, step, etc.” are to be interpreted openly asreferring to at least one instance of the element, apparatus, component,means, step, etc., unless explicitly stated otherwise. The steps of anymethod disclosed herein do not have to be performed in the exact orderdisclosed, unless explicitly stated.

BRIEF DESCRIPTION OF THE DRAWINGS

The inventive concept is now described, by way of example, withreference to the accompanying drawings, in which:

FIGS. 1, 2, 3 are schematic diagrams illustrating radio transceiverdevices and parts thereof according to embodiments;

FIGS. 4, 5, 6, 7, and 8 schematically illustrate signal spectrumsaccording to embodiments;

FIGS. 9 and 10 are flowcharts of methods according to embodiments;

FIG. 11 is a schematic diagram showing functional units of a controldevice according to an embodiment;

FIG. 12 is a schematic diagram showing functional modules of a controldevice according to an embodiment;

FIG. 13 shows one example of a computer program product comprisingcomputer readable storage medium according to an embodiment.

DETAILED DESCRIPTION

The inventive concept will now be described more fully hereinafter withreference to the accompanying drawings, in which certain embodiments ofthe inventive concept are shown. This inventive concept may, however, beembodied in many different forms and should not be construed as limitedto the embodiments set forth herein; rather, these embodiments areprovided by way of example so that this disclosure will be thorough andcomplete, and will fully convey the scope of the inventive concept tothose skilled in the art.

Like numbers refer to like elements throughout the description. Any stepor feature illustrated by dashed lines should be regarded as optional.

As noted above, a diplexer filter is commonly used to prevent signalstransmitted by a radio transceiver device from leaking into the receiverof the radio transceiver device. Disadvantages of such a diplexer havealso been noted above.

The herein disclosed embodiments provide mechanisms that reduce crossmodulation effects when the diplexer is replaced by a component thathave lower isolation between transmitter and receiver, for example, by anotch filter.

Replacing the diplexer with a notch filter still leads to some powerreduction of the transmitted signal into the receiver. However, thetransmitted signal power suppression using a notch filter is lowercompared to what is achieved using a diplexer. In general terms, thetransmitted signal leaking into the receiver will experience nonlineardistortion in elements like the Low Noise Amplifier (LNA). A side effectof this is cross modulation nonlinear distortion, i.e. that thetransmitted signal mixes with the received signal in the nonlinearelements in the receiver of the radio transceiver device. This way,components of the transmitted signal are translated in frequency and endup in the receive band of a FDD based communication system. Suchcomponents can then not be suppressed by simple filtering, since suchfiltering would also suppress the received desired signal. This is aproblem which, if left unaddressed, will lead to performance degradationof the communication system.

The embodiments disclosed herein in particular relate to mechanisms forsuppressing interference in a received reception signal in a radiotransceiver device. In order to obtain such mechanisms there is provideda control device, a method performed by the control device, a computerprogram product comprising code, for example in the form of a computerprogram, that when run on a control device, causes the control device toperform the method.

FIG. 1 is a schematic diagram illustrating a radio transceiver device100 according to an embodiment. The radio transceiver device 100comprises a baseband part 110 and a radio frequency part 120. Thebaseband part 110 comprises baseband circuitry and is configured forprocessing of transmission signals and reception signals at baseband, orpotentially at an intermediate frequency. The radio frequency part 120comprises radio circuitry and is configured for processing oftransmission signals and reception signals at radio frequency. Thebaseband part 110 comprises a control device 300. A description of thefunctionality of the control device 300 will be provided below withreference to FIGS. 9 and 10.

According to aspects of the disclosed radio transceiver device 100 foruse in a microwave radio link, radio frequency is often in the order toseveral tens of GHz, intermediate frequency is in the MHz range, whilebaseband is a frequency band comprising and often centred around zerofrequency.

FIG. 2 is a schematic diagram illustrating details of the radiofrequency part 120 of the radio transceiver device 100 according to anembodiment.

The radio frequency part 120 is configured to generate (by up convertinga transmission signal S_(Tx) by multiplication with e^(j2πfTxt)) and totransmit a radio transmission signal S_(Tx-RF) to a remote transceiverand to receive a radio reception signal S_(Tot-RF) from the remotetransceiver.

The radio transmission signal S_(Tx-RF) leaks into the radio receptionsignal S_(Tot-RF), here modelled by h. According to an embodiment themodel h is a linear model, e.g. a tapped delay-line model. The modelh(S_(Tx-RF)) could be based on band-stop filtering of the radiotransmission signal S_(Tx-RF). In this way the leakage of the radiotransmission signal S_(Tx-RF) into the radio reception signal S_(Tot-RF)could be modelled as being caused by a notch filter replacing thediplexer. For example, according to aspects h is a linear filter. Thetotal received radio reception signal S_(Tot-RF) is therefore the sum ofa desired radio reception signal S_(Rx-RF) and a filtered version of theradio transmission signal S_(Tx-RF). The reception signal S_(Tot-RF)thus comprises the desired radio reception signal S_(Rx-RF) and aninternal leakage contribution, as modelled by the model h(S_(Tx-RF)), ofthe radio transmission signal S_(Tx-RF).

The total received signal may also comprise one or more adjacentinterferer signals. Hence, according to an embodiment the receptionsignal S_(Tot-RF) further comprises an external leakage contributionS_(Adj-RF) of another radio reception signal. According to some aspectsthis so-called another radio reception signal defines an adjacentinterferer signal. However, according to other aspects this so-calledanother radio reception signal could be any modulated signal. Thedesired radio reception signal S_(Rx-RF) and this another radioreception signal can be located on neighbouring carrier frequencies, orbe separated by at least one channel (where each channel could bedefined by its own carrier frequency).

The relative difference in power between the transmitted signal and thedesired reception signal, i.e., between S_(Tx-RF) and S_(Rx-RF) is oftenlarge, i.e. P_(Tx-RF)>>P_(Rx-RF) and P_(Tx-RF)>>P_(Adj-RF), whereP_(Tx-RF) denotes the power of S_(Tx-RF), where P_(Rx-RF) denotes thepower of S_(Rx-RF), and where P_(Adj-RF) denotes the power ofS_(Adj-RF). According to an embodiment the radio transmission signalS_(Tx-RF) is more than one order of magnitude larger in power than theradio reception signal S_(Tot-RF).

An example of a resulting signal spectrum 400 of the desired radioreception signal S_(Rx-RF) and the external leakage contributionS_(Adj-RF) of another radio reception signal is illustrated in FIG. 4.In FIG. 4 the left-most peak 400 a is caused by S_(Rx-RF) and theright-most peak 400 b is caused by S_(Adj-RF). As a comparison, anexample of a resulting signal spectrum 500 of the total received radioreception signal S_(Tot-RF) (i.e., also including the radio transmissionsignal S_(Tx-RF)) is illustrated in FIG. 5. In FIG. 5 the left-most peak500 a is caused by S_(Rx-RF), the middle-most peak 500 b is caused byS_(Adj-RF), and the right-most peak 500 c is caused by S_(Tx-RF).

The total received radio reception signal S_(Tot-RF) is distorted by afunction denoted ƒ, before down conversion (by multiplication withe^(−2πfRxt)). According to aspects the function ƒ is nonlinear andmodelled as memoryless. For example, the nonlinear function ƒ can bemodelled by a third order memoryless nonlinearity and hence be writtenas follows:

ƒ(x;A)=x+Ax|x| ².  (1)

In Equation (1), the symbol x denotes input to the nonlinear function(here defined by the total received radio reception signal S_(Tot-RF)),and A is a parameter of function ƒ, i.e., A parameterizes ƒ. It can beassumed that |A|<<1. In general terms, LNAs in a radio receiver aretypically of class A type (i.e., so-called class A amplifiers). Normallya third order intermodulation is dominating over all otherintermodulation products. The same is true for other non-linear elementslike mixers. A more general form of memoryless non-linearity thanexpressed in Equation (1) is therefore:

${F\left( {x;A} \right)} = {x + {\sum\limits_{n = 1}^{N}{A_{n}x{{x}^{n}.}}}}$

This general form is hereinafter approximated by Equation (1). Equation(1) is thus an approximation of the true distortion. Equations (2), (3),(4), (8), and (9) below are based on this approximation.

The resulting total received radio reception signal ƒ(S_(Tot-RF)) afterhaving been subjected to the nonlinearity ƒ is modelled as follows:

ƒ(S _(Tot-RF) ;A)=h⊗s _(Tx-RF) +s _(Rx-RF) +S _(Adj-RF) +A(h⊗s _(Tx-RF)+s _(Rx-RF) +S _(Adj-RF))|h⊗s s _(Tx-RF) +s _(Rx-RF) +S _(Adj-RF)|²  (2)

In Equation (2) the symbol ⊗ denotes convolution. In Equation (2) anyreceiver noise has been assumed to be insignificant.

FIG. 6 schematically illustrates the resulting signal spectrum 600 wherethe non-linear function ƒ is set to ƒ(S_(Tot-RF); A) defined in Equation(2), and the filter h is determined as h=1. Peaks 600 a and 600 b arecaused by S_(Rx-RF) and S_(Aaj-RF), respectively, and peak 600 c iscaused by S_(Tx-RF). All different signal spectrums contain distortionshown as side lobes to the original spectra. The distortion of S_(Rx-RF)and S_(Adj-RF) is due to the cross modulation from S_(Tx-RF) (as seen inEquation (2) and (3).

As a comparison FIG. 7 schematically illustrates the resulting signalspectrum 700 where a notch filter has been used as filter h. Peaks 700 aand 700 b are caused by S_(Rx-RF) and S_(Adj-RF), respectively, and peak700 c is caused by S_(Tx-RF). The distortion of S_(Rx-RF) and S_(Adj-RF)is reduced significantly (side lobes are now reduced). However, thedistortion due to cross modulation is still considered far too high tomeet requirements on received signal quality.

Further, a linear filter a, illustrated in FIG. 2, is configured toremove all signals not centered around S_(Rx) (and S_(Adj), whereS_(Adj) is a baseband version of S_(Aaj-RF)) and thus to remove up anddown converted versions of the radio transmission signal S_(Tx-RF).Thus, after application of the linear filter a the radio transmissionsignal S_(Tx-RF) and non-relevant signals are heavily suppressed andthus in principle removed. Thus all the peaks centered around −0.3·10⁹Hz and 0.6·10⁹ Hz together with the transmission signal close to 0.3·10⁹Hz in FIG. 7 can be removed by filtering. But note that the crossmodulation of S_(Tx-RF) and S_(Adj-RF) still leaks into the desiredreception signal S_(Rx). The remaining reception signal S_(Tot) can thusbe expressed as follows:

S _(Tot) =S _(Rx)+2AS _(Rx) |h⊗S _(Tx-RF)|² +S _(Adj-RF)+2AS _(Adj) |h⊗S_(Tx-RF)|².  (3)

One general task and purpose of the receiver is to derive information inS_(Rx) from the observed reception signal S_(Tot), i.e. to removeunwanted distortion and the adjacent channel (S_(Adj)).

FIG. 3 is a schematic diagram illustrating details of the baseband part110 of the radio transceiver device 100 according to an embodiment.

The transmission signal S_(Tx) is generated by a mapper (denoted Map inFIG. 3) mapping symbols of a digital input signal D_(in) to a signalconstellation point and filtering the thus generated sequence ofconstellation points by a transmitter filter p_(Tx). The transmissionsignal S_(Tx) will below be denoted a transmission reference signal.

The reception signal S_(Tot) is processed by a control device 300 toprovide a compensated reception signal S_(Comp). Further details of thecontrol device 300 and how the compensated reception signal S_(Comp) isdetermined will be disclosed below.

The compensated reception signal S_(Comp) is filtered by a receiverfilter p_(Rx), resulting in a filtered receiver signal Ŝ_(Rx), and fedto a detector, denoted Dec, resulting in a detected receiver signalS_(Rx,Dec). The detector can be assumed a hard decision detector, i.e.it decides based on minimum Euclidean to a given set of symbols (forexample an M-ary quadrature amplitude modulation (QAM) constellation).The detector could, according to some aspects, use prior knowledge (suchas a training sequence or known symbols appearing periodically) as acomplement to the hard decision. The detected receiver signal S_(Rx,Dec)is then fed to an inverse mapper Map⁻¹ performing the inverse operationsof the mapper Map to produce a digital output sequence D_(Out).

Reference is now made to FIG. 9 illustrating a method for suppressinginterference in a received reception signal S_(Tot) in the radiotransceiver device 100 as performed by the control device 300 accordingto an embodiment.

As disclosed above, the radio transceiver device 100 is configured toreceive the reception signal S_(Tot) as a radio reception signalS_(Tot-RF) and to generate a radio transmission signal S_(Tx-RF). Theradio transmission signal S_(Tx-RF) and the radio reception signalS_(Tot-RF) occupy at least partly non-overlapping frequency bands.

S102: The control device 300 obtains the transmission reference signalS_(Tx) based on the radio transmission signal S_(Tx-RF).

S104: The control device 300 estimates an interference distortioncomponent signal Ŝ_(CM). The interference distortion component signalŜ_(CM) is estimated based on the transmission reference signal S_(Tx)and on the model of nonlinearity in a radio circuit of the radiotransceiver device 100. An example of this model h has been providedabove.

S106: The control device 300 suppresses interference in the receptionsignal S_(Tot). Interference in the reception signal S_(Tot) issuppressed by combining the reception signal S_(Tot) with the distortioncomponent signal Ŝ_(CM).

In general terms, combining the reception signal S_(Tot) with thedistortion component signal Ŝ_(CM) results in a compensated receptionsignal S_(Comp). According to an embodiment the compensated receptionsignal S_(Comp) is determined so as to compensate the reception signalS_(Tot) for the internal leakage contribution due to h(S_(Tx-RF)).

According to an embodiment the interference distortion component signalŜ_(CM) represents at least one non-linear component, for example thenonlinear function ƒ, in the radio circuit of the radio transceiverdevice 100.

According to an embodiment the interference distortion component signalŜ_(CM) is an estimation of cross modulation in a receiver branch of theradio transceiver device 100.

Embodiments relating to further details of suppressing interference in areceived reception signal S_(Tot) in the radio transceiver device 100will now be disclosed.

Reference is now made to FIG. 10 illustrating methods for suppressinginterference in a received reception signal S_(Tot) in the radiotransceiver device 100 as performed by the control device 300 accordingto further embodiments. It is assumed that steps S102, S104, s106 areperformed as described with reference to FIG. 9, and a repeateddescription of these steps is therefore omitted.

One general task and purpose of the receiver is to derive information inS_(Rx) from the observed reception signal S_(Tot), i.e. to removeunwanted distortion and the adjacent channel (S_(Adj-RF)). The crossmodulation of S_(Tx-RF) and S_(Adj-RF) leaks into the desired receptionsignal S_(Rx). Without any cross modulation S_(Adj-RF) could be removedby filtering. Without any cross modulation S_(Tx-RF) could also beremoved by filtering.

Instead the control device 300 is configured to estimate the crossmodulation S_(CM), i.e. to find Ŝ_(CM). From Equation (3) follows thatthe cross modulation Ŝ_(CM) can be defined according to Equation (4):

s _(CM) =As _(Rx) |h⊗s _(Tx-RF)|² +As _(Adj) |h⊗s _(Tx-RF)|²  (4)

The radio transmission signal S_(Tx-RF) can be assumed known or at leastthe complex base band version of it, i.e. the transmission signalS_(Tx), can be considered known. Thus, according to aspects, one task ofthe control device 300 is to find a function, r(S_(Tot), S_(Tx); Θ),where Θ denotes a parameter (which may be vector valued), that estimatesŜ_(CM) such that

Ŝ _(CM) =r(S _(Tot) ,S _(Tx),Θ).  (5)

The control device 300 could thereby estimate the cross modulationŜ_(CM) using the estimator, r, and compensates the received signalS_(Tot) with the estimated distortion Ŝ_(CM). According to an embodimentthe interference distortion component signal Ŝ_(CM) is estimated byminimizing an error signal e based on a difference between thecompensated reception signal S_(Comp) and a receiver signal. Asdisclosed above, Ŝ_(Rx), is a filtered receiver signal and S_(Rx,Dec) isa detected receiver signal. Hence, according to an embodiment thecontrol device 300 is configured to determine the filtered receiversignal Ŝ_(Rx) by performing step S108 and to process the filteredreceiver signal Ŝ_(Rx) to obtain the detected receiver signal S_(Rx,Dec)by performing step S110:

S108: The control device 300 filters the compensated reception signalS_(Comp), resulting in the filtered receiver signal check for missingŜ_(Rx).

S110: The control device 300 processes the filtered receiver signalŜ_(Rx) by the detector, resulting in the detected receiver signalS_(Rx,Dec).

The error signal e is then determined as a difference between thefiltered receiver signal Ŝ_(Rx) and the detected receiver signalS_(Rx,Dec). That is, according to an embodiment the error signal e isformulated as in Equation (6):

e=Ŝ _(Rx) −S _(Rx,Dec).  (6)

There can be different ways to use the error signal e to determine theinterference distortion component signal Ŝ_(CM). According to anembodiment the interference distortion component signal Ŝ_(CM) isestimated using a least means squares (LMS) estimate based on the errorsignal e. In further detail, the square of the error signal e can beminimized in order to determine an optimum parameter set Θ forestimating Ŝ_(CM).

An LMS approach finding the parameters can be derived according toEquation (7):

E[e(n)e(n)*]=E└e(n)(S _(CM)(n)−r(S _(Tot) ,S _(Tx),Θ))*┘.  (7)

The resulting compensation then becomes according to Equation (8):

$\begin{matrix}{{\hat{S}}_{CM} = {{S_{Tot}(n)}{\left( {\sum\limits_{k = 0}^{N}{\sum\limits_{l = 0}^{N}{\beta_{k,l}{S_{Tx}\left( {n - k} \right)}{S_{Tx}\left( {n - l} \right)}^{*}}}} \right).}}} & (8)\end{matrix}$

The LMS expression estimating the coefficients (β_(k,i) or Θ) becomesaccording to Equation (8):

βk,l(m+1)=β_(k,l)(m)−μe(n)S _(Tot)(n)*S _(Tx)(n−k)*S _(Tx)(n−l).  (9)

In Equation (9) the symbol * denotes complex conjugation. Using a filterh with h=1 and appropriate configuration of A, the down convertedcompensated spectrum 810 and uncompensated spectrum 800 as illustratedin FIG. 8 are achieved, where

${{10\mspace{14mu} {\log_{10}\left( \frac{P_{{Tx} - {RF}}}{P_{{Rx} - {RF}}} \right)}} = {{40\mspace{14mu} {dB}\mspace{14mu} {and}\mspace{14mu} 10\mspace{14mu} {\log_{10}\left( \frac{P_{{Adj} - {RF}}}{P_{{Rx} - {RF}}} \right)}} = {3\mspace{14mu} {dB}}}},$

where P_(Tx-RF) denotes the power of S_(Tx-RF), where P_(Rx-RF) denotesthe power of S_(Rx-RF), and where P_(Adj-RF) denotes the power ofS_(Adj-RF).

FIG. 11 schematically illustrates, in terms of a number of functionalunits, the components of a control device 300 according to anembodiment. Processing circuitry 1110 is provided using any combinationof one or more of a suitable central processing unit (CPU),multiprocessor, microcontroller, digital signal processor (DSP), etc.,capable of executing software instructions stored in a computer programproduct 1310 (as in FIG. 13), e.g. in the form of a storage medium 1130.The processing circuitry 1110 may further be provided as at least oneapplication specific integrated circuit (ASIC), or field programmablegate array (FPGA).

Particularly, the processing circuitry 1110 is configured to cause thecontrol device 300 to perform a set of operations, or steps, S102-S110,as disclosed above. For example, the storage medium 1130 may store theset of operations, and the processing circuitry 1110 may be configuredto retrieve the set of operations from the storage medium 1130 to causethe control device 300 to perform the set of operations. The set ofoperations may be provided as a set of executable instructions.

Thus the processing circuitry 1110 is thereby arranged to executemethods as herein disclosed. The storage medium 1130 may also comprisepersistent storage, which, for example, can be any single one orcombination of magnetic memory, optical memory, solid state memory oreven remotely mounted memory. The control device 300 may furthercomprise a communications interface 1120 at least configured to obtainS_(Tx), Θ, S_(Tot), and to provide S_(Comp). As such the communicationsinterface 1120 may comprise one or more transmitters and receivers,comprising analogue and digital components. The processing circuitry1110 controls the general operation of the control device 300 e.g. bysending data and control signals to the communications interface 1120and the storage medium 1130, by receiving data and reports from thecommunications interface 1120, and by retrieving data and instructionsfrom the storage medium 1130. Other components, as well as the relatedfunctionality, of the control device 300 are omitted in order not toobscure the concepts presented herein.

FIG. 12 schematically illustrates, in terms of a number of functionalmodules, the components of a control device 300 according to anembodiment. The control device 300 of FIG. 12 comprises a number offunctional modules; an obtain module 1110 a configured to perform stepS102, an estimate module 1110 b configured to perform step S104, and asuppress module 1110 c configured to perform step S106. The controldevice 300 of FIG. 12 may further comprises a number of optionalfunctional modules, such as any of a filter module configured to performstep S108, and a detector module 1110 e configured to perform step S110.

In general terms, each functional module 1110 a-1110 e may in oneembodiment be implemented only in hardware or and in another embodimentwith the help of software, i.e., the latter embodiment having computerprogram instructions stored on the storage medium 1130 which when run onthe processing circuitry makes the control device 300 perform thecorresponding steps mentioned above in conjunction with FIG. 12. Itshould also be mentioned that even though the modules correspond toparts of a computer program, they do not need to be separate modulestherein, but the way in which they are implemented in software isdependent on the programming language used. Preferably, one or more orall functional modules 1110 a-1110 e may be implemented by theprocessing circuitry 1110, possibly in cooperation with functional units1120 and/or 1130. The processing circuitry 1110 may thus be configuredto from the storage medium 1130 fetch instructions as provided by afunctional module 1110 a-1110 e and to execute these instructions,thereby performing any steps as disclosed herein.

The control device 300 may be provided as a standalone device or as apart of at least one further device. For example, the control device 300may be provided in the radio transceiver device 100. Hence, according toan embodiment there is provided a radio transceiver device 100 as hereindisclosed comprising a control device 300 as herein disclosed.

Alternatively, functionality of the control device 300 may bedistributed between at least two devices, or nodes. Thus, a firstportion of the instructions performed by the control device 300 may beexecuted in a first device, and a second portion of the of theinstructions performed by the control device 300 may be executed in asecond device; the herein disclosed embodiments are not limited to anyparticular number of devices on which the instructions performed by thecontrol device 300 may be executed. Hence, the methods according to theherein disclosed embodiments are suitable to be performed by a controldevice 300 residing in a cloud computational environment. Therefore,although a single processing circuitry 1110 is illustrated in FIG. 11the processing circuitry 1110 may be distributed among a plurality ofdevices, or nodes. The same applies to the functional modules 1110a-1110 e of FIG. 12 and the computer program 1320 of FIG. 13 (seebelow).

FIG. 13 shows one example of a computer program product 1310 comprisingcomputer readable storage medium 1330. On this computer readable storagemedium 1330, a computer program 1320 can be stored, which computerprogram 1320 can cause the processing circuitry 1110 and theretooperatively coupled entities and devices, such as the communicationsinterface 1120 and the storage medium 1130, to execute methods accordingto embodiments described herein. The computer program 1320 and/orcomputer program product 1310 may thus provide means for performing anysteps as herein disclosed.

In the example of FIG. 13, the computer program product 1310 isillustrated as an optical disc, such as a CD (compact disc) or a DVD(digital versatile disc) or a Blu-Ray disc. The computer program product1310 could also be embodied as a memory, such as a random access memory(RAM), a read-only memory (ROM), an erasable programmable read-onlymemory (EPROM), or an electrically erasable programmable read-onlymemory (EEPROM) and more particularly as a non-volatile storage mediumof a device in an external memory such as a USB (Universal Serial Bus)memory or a Flash memory, such as a compact Flash memory. Thus, whilethe computer program 1320 is here schematically shown as a track on thedepicted optical disk, the computer program 1320 can be stored in anyway which is suitable for the computer program product 1310.

The inventive concept has mainly been described above with reference toa few embodiments. However, as is readily appreciated by a personskilled in the art, other embodiments than the ones disclosed above areequally possible within the scope of the inventive concept, as definedby the appended patent claims.

1. A method performed by a control device for suppressing interference in a received reception signal S_(Tot) in a radio transceiver device configured to receive the reception signal S_(Tot) as a radio reception signal S_(Tot-RF) and to generate a radio transmission signal S_(Tx-RF), wherein the radio transmission signal S_(Tx-RF) and the radio reception signal S_(Tot-RF) occupy at least partly non-overlapping frequency bands, the method comprising: obtaining a transmission reference signal S_(Tx) based on the radio transmission signal S_(Tx-RF); estimating an interference distortion component signal Ŝ_(CM) based on the transmission reference signal S_(Tx) and on a model of nonlinearity in a radio circuit of the radio transceiver device; and suppressing interference in the reception signal S_(Tot) by combining the reception signal S_(Tot) with the distortion component signal Ŝ_(CM).
 2. The method according to claim 1, wherein combining the reception signal S_(Tot) with the distortion component signal Ŝ_(CM) results in a compensated reception signal S_(Comp).
 3. The method according to claim 1, wherein the interference distortion component signal Ŝ_(CM) is an estimation of cross modulation in a receiver branch of the radio transceiver device.
 4. The method according to claim 1, wherein the reception signal S_(Tot) comprises a desired radio reception signal S_(Rx-RF) and an internal leakage contribution, as modelled by the model, of the radio transmission signal S_(Tx-RF).
 5. The method according to claim 2, wherein the compensated reception signal S_(Comp) is determined so as to compensate the reception signal S_(Tot) for the internal leakage contribution h(S_(Tx-RF)).
 6. The method according to claim 1, wherein the interference distortion component signal Ŝ_(CM) represents at least one non-linear component f in the radio circuit.
 7. The method according to claim 2, wherein the interference distortion component signal Ŝ_(CM) is estimated by minimizing an error signal e based on a difference between the compensated reception signal S_(Comp) and a receiver signal.
 8. The method according to claim 7, wherein the receiver signal is a filtered receiver signal S_(Rx) and determined by: filtering the compensated reception signal S_(Comp), resulting in the filtered receiver signal Ŝ_(Rx).
 9. The method according to claim 7, further comprising: processing the filtered receiver signal Ŝ_(Rx) by a detector, resulting in a detected receiver signal S_(Rx,Dec), and wherein the difference is determined between the filtered receiver signal Ŝ_(Rx) and the detected receiver signal S_(Rx,Dec).
 10. The method according to claim 6, wherein the interference distortion component signal Ŝ_(CM) is estimated using a least means squares estimate based on the error signal e.
 11. The method according to claim 1, wherein the radio transmission signal S_(Tx-RF) is more than one order of magnitude larger in power than the radio reception signal S_(Tot-RF).
 12. The method according to claim 1, wherein the model is based on band-stop filtering of the radio transmission signal S_(Tx-RF).
 13. The method according to claim 4, wherein the reception signal S_(Tot) further comprises an external leakage contribution S_(Adj-RF) of another radio reception signal, wherein the desired radio reception signal S_(Rx-RF) and said another radio reception signal are located on neighbouring carrier frequencies.
 14. A control device for suppressing interference in a received reception signal S_(Tot) in a radio transceiver device configured to receive the reception signal S_(Tot) as a radio reception signal S_(Tot-RF) and to generate a radio transmission signal S_(Tx-RF), wherein the radio transmission signal S_(Tx-RF) and the radio reception signal S_(Tot-RF) occupy at least partly non-overlapping frequency bands, the control device comprising processing circuitry, the processing circuitry being configured to cause the control device to: obtain a transmission reference signal S_(Tx) based on the radio transmission signal S_(Tx-RF); estimate an interference distortion component signal Ŝ_(CM) based on the transmission reference signal S_(Tx) and on a model of nonlinearity in a radio circuit of the radio transceiver device; and suppress interference in the reception signal S_(Tot) by combining the reception signal S_(Tot) with the distortion component signal Ŝ_(CM).
 15. A control device for suppressing interference in a received reception signal S_(Tot) in a radio transceiver device configured to receive the reception signal S_(Tot) as a radio reception signal S_(Tot-RF) and to generate a radio transmission signal S_(Tx-RF), wherein the radio transmission signal S_(Tx-RF) and the radio reception signal S_(Tot-RF) occupy at least partly non-overlapping frequency bands, the control device comprising: processing circuitry; and a computer program product storing instructions that, when executed by the processing circuitry, causes the control device to: obtain a transmission reference signal S_(Tx) based on the radio transmission signal S_(Tx-RF); estimate an interference distortion component signal Ŝ_(CM) based on the transmission reference signal S_(Tx) and on a model of nonlinearity in a radio circuit of the radio transceiver device; and suppress interference in the reception signal S_(Tot) by combining the reception signal S_(Tot) with the distortion component signal Ŝ_(CM).
 16. A control device for suppressing interference in a received reception signal S_(Tot) in a radio transceiver device configured to receive the reception signal S_(Tot) as a radio reception signal S_(Tot-RF) and to generate a radio transmission signal S_(Tx-RF), wherein the radio transmission signal S_(Tx-RF) and the radio reception signal S_(Tot-RF) occupy at least partly non-overlapping frequency bands, the control device comprising: an obtain module configured to obtain a transmission reference signal S_(Tx) based on the radio transmission signal S_(Tx-RF); an estimate module configured to estimate an interference distortion component signal Ŝ_(CM) based on the transmission reference signal S_(Tx) and on a model of nonlinearity in a radio circuit of the radio transceiver device; and a suppress module configured to suppress interference in the reception signal S_(Tot) by combining the reception signal S_(Tot) with the distortion component signal Ŝ_(CM).
 17. (canceled)
 18. For suppressing interference in a received reception signal S_(Tot) in a radio transceiver device configured to receive the reception signal S_(Tot) as a radio reception signal S_(Tot-RF) and to generate a radio transmission signal S_(Tx-RF), wherein the radio transmission signal S_(Tx-RF) and the radio reception signal S_(Tot-RF) occupy at least partly non-overlapping frequency bands, a non-transitory computer-readable storage medium comprising a computer program product including instructions to cause processing circuitry to: obtain a transmission reference signal S_(Tx) based on the radio transmission signal S_(Tx-RF); estimate an interference distortion component signal Ŝ_(CM) based on the transmission reference signal S_(Tx) and on a model of nonlinearity in a radio circuit of the radio transceiver device; and suppress interference in the reception signal S_(Tot) by combining the reception signal S_(Tot) with the distortion component signal Ŝ_(CM).
 19. (canceled) 